The anticipatory phase is often considered the first true step in swallowing because visual information, olfactory stimulation, and experience interact to form the initial motor plan (3). A common statement in the culinary profession is, “we eat with our eyes first.” The adult has
a well-developed motor plan for swallowing different types of food and drink that is based upon appearance (visual processing), consistency (tactile processing), taste (chemical processing), and bolus size (proprioceptive processing). Most have experienced a sudden awareness that an item placed in the mouth did not match what was expected. This observation can be viewed as practical evidence that a plan had been violated. Another example that illustrates this concept can be seen when we perceive a liquid to be very hot or a food is suspected of being very spicy. When experience indicates these possibilities, a slower presentation to the mouth will follow and care will be taken to ensure a smaller bolus size because of the anticipated negative effects.

It is also at the anticipatory level where distinctions between food and nonfood items are made and where palatability is determined. Oral intake may be avoided as a result of the information perceived and processed during this phase. If an individual is forced to eat or drink an item that he or she has predetermined (anticipated) is unsafe or undesirable, then gagging, coughing, and dysphagic symptoms may be observed. It is important to note that these are not behaviors that can be controlled; rather, they are in response to sensory stimulation. The anticipatory phase provides the initial sensory input to cortical swallowing structures. In patients with dementia or other cognitive impairments, the sensory processing of visual, olfactory, and experiential information can be altered. As such, the motor plan implemented to swallow may not match that of the bolus itself, putting the patient at risk for dysphagia.

Once solid and semisolid food is placed in the mouth, it must first be prepared for the pharyngeal phase. The combination of mastication and saliva production is considered to be the first step in digestion. Saliva from the submental, sublingual, and parotid glands flows into the oral cavity to mix with the bolus and begin the chemical process of food breakdown. The mandible closes to crush solid food and the rotatory motion of mastication enables the molars to shear and shred the food. The muscles of mastication are the masseter, temporalis, medial pterygoid, and lateral pterygoid muscles (Table 56.1). The masseter, temporalis, and medial pterygoid muscles elevate the mandible,
while the lateral pterygoid depresses the mandible, thereby opening the mouth. Contraction of the masseter and medial pterygoid muscles also results in lateral mandible movements required for the rotary motions. Sensory and motor innervation to the muscles of mastication and salivary glands is provided by several branches of the trigeminal nerve. The cyclic motion of the mandible and motions of the tongue are mediated, in part, by a cortical central pattern generator (CPG). A CPG is essentially neural circuitry that generates rhythmic movement. It is important to remember that during this phase, the airway is open and active breathing continues. During mastication, respiratory rate becomes more rapid and irregular when compared to tidal breathing (4). If the bolus is not well controlled, solid food may fall into the open airway resulting in aspiration or asphyxiation. Also during mastication, the circular fibers of the orbicularis oris muscle work to actively close the lips and maintain the food or liquid within the oral cavity. An incompetent oral sphincter will result in drooling of saliva or loss of food and liquid out of the mouth. This circumstance is very embarrassing for patients and severely impacts the social aspects of meals. Neurologic diseases and surgical resections that prevent labial closure or impair sensation can cause anterior oral loss of food or liquid.